This invention relates generally to semiconductor device fabrication and more particularly to an improved method for selectively identifying or marking semiconductor integrated circuit bars on a wafer.
In the fabrication of semiconductor devices each integrated circuit bar on a wafer is tested prior to scribing and breaking the wafer into individual bars for assembly and packaging. Various methods are known for identifying which bars failed the test and thus should be scrapped. A commonly used method is to apply an ink dot to the defective bars by means of a thin cord of nylon or similar material attached to the plunger of an electrical solenoid. The end of the cord is in a reservoir of ink. When activated the solenoid pushes the cord out through a hollow tube, carrying with it a small amount of ink, and the inked cord touches the surface of the integrated circuit bar.
While this method effectively marks the bars, it has the disadvantages of using a liquid, i.e., the ink tends to splatter and run. Further, the inking apparatus is typically bulky and unreliable and the ink reservoir requires frequent cleaning and refilling.